<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #result {
            width: 200px;
            height: 100px;
            border: 1px solid #903;
        }
    </style>
</head>

<body>
    <div id="result"></div>
    <script>
        const result = document.querySelector('#result');
        result.addEventListener('mouseover', function () {
            // 1.创建对象
            const xhr = new XMLHttpRequest();
            // 2.初始化 设置请求类型与URL
            xhr.open('POST', 'http://127.0.0.1:8000/server');
            //设置请求头
            xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
            xhr.setRequestHeader('name', 'atguigu');
            // 3.发送请求
            xhr.send('a=100&b=200&c=300');
            xhr.onreadystatechange = function () {
                if (xhr.readyState === 4) {
                    if (xhr.status >= 200 && xhr.status < 300) {
                        // 处理服务端返回的结果
                        result.innerHTML = xhr.response;
                    }
                }
            };

        });
    </script>
</body>

</html>